Synchronous collapsed ring architecture for real-time signal switching and distribution

ABSTRACT

A method and system includes at least one interconnect hub, connecting the at least one interconnect hub to a plurality of audio connection devices to form a network of audio connection devices with the interconnect hub at the center of the ring. The audio connection devices are connected to each other through the at least one interconnect hub, and data is synchronously transmitted between at least two of the audio connection devices through the at least one interconnect hub.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/904,289, filed Jul. 12, 2001, entitled “SYNCHRONOUS COLLAPSED RINGARCHITECTURE FOR REAL TIME SIGNAL SWITCHING AND DISTRIBUTION,” which inturn claims the benefit of U.S. provisional application Ser. No.60/218,362, filed Jul. 13, 2000, entitled “SYNCHRONOUS COLLAPSED RINGARCHITECTURE METHOD AND SYSTEM FOR REAL-TIME SIGNAL SWITCHING ANDDISTRIBUTION,” each which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

This invention relates in general to the field of communications, andmore particularly to a method and system for synchronous collapsed ringarchitecture for real-time signal switching and distribution.

BACKGROUND

Commercial and military aircraft provide fast, reliable, and efficientmeans for transportation of people and cargo. For the military, aircraftprovide strategic military capabilities. Communications systems withinall aircraft are essential to ensure, proper operation of the aircraft,deployment of personnel, and strategic sufficiency.

Modern aircraft communications systems have many requirements, with mostof these requirements applicable in military and non-military contexts.For example, aircraft communications systems, as well as land-basedsystems, should have growth capacity, be flexible to adaptation, providesecure communications, and meet suitable space and weight requirements.Of course, such systems must also be reliable and be able to interfacewith a wide variety of equipment, such as radios, cryptographic devices,headsets and speakers, and video devices.

Despite these needs, many aircraft platforms use noisy, unreliable, andexpensive analog communications systems. Such systems are employed inmilitary and non-military aircraft and non-aircraft communicationssystems.

Therefore, a need has arisen for a method and system that overcomes thedisadvantages and deficiencies of the present day communicationssystems.

SUMMARY

The present invention relates to a method and system for communicatinginformation that addresses disadvantages of prior systems and methods.

In accordance with the present invention, a method for communicationcomprises providing at least one hub, connecting the at least one hub toa plurality of audio connection devices to form a ring. The audioconnection devices with the hub at the center of the ring, wherein theaudio connection devices are connected to each other through the atleast one hub, and synchronously transmit data between at least two ofthe audio connection devices through the at least one hub.

According to another embodiment of the invention a communications systemcomprises a star network having a hub located at the center of the starnetwork. The star network carries a synchronous data stream.

Embodiments of the present invention provides various technicaladvantages. For example, one embodiment of the invention utilizes 155Mb/s fiber-optic based architecture designed to handle multiple datatypes simultaneously and provides large signal capacity such as greaterthan 1000 channels of 4 KHz audio, greater than 256 Wideband (20 KHz+)channels, and multiple video or data channels.

According to another embodiment, the invention comprises acommunications system and method that provides binaural sound, therebyproviding spatial placement of audio channels to aid operatorcomprehension when listening to multiple audio channels. Furthermore,one embodiment of the invention utilizes DSP-based audio processing toprovide flexibility to handle special audio processing needs (filters,mixing, etc).

According to another embodiment of the invention, a communicationssystem and method are provided that include built-in redundancy andfault tolerance for high utilization reliability. Also, advancedconferencing capabilities are provided, resulting in substantiallyunlimited conference channels and also provides point to point calling.

Communications systems in accordance with the invention are also fullyred/black compliant and are designed to meet Tempest requirements.Communications systems of the present invention are based on industryopen standard interfaces and technology, compatibility with COTSequipment, thereby enhancing affordability and minimizeupgrade/modification costs, and enhance technology longevity andstability.

Other advantages may be readily ascertainable by those in the art andthe following figures, description, and claims.

DESCRIPTION OF THE DRAWINGS

It is noted that the appended drawings illustrate only exemplaryembodiments of the techniques described herein and are, therefore, notto be considered limiting of its scope, for the invention may admit toother equally effective embodiments.

FIG. 1 is a block diagram of a communications network according to theteachings of the invention.

FIG. 2A is a block diagram of the switching system shown in FIG. 1.

FIG. 2B is another block diagram of the switching system shown in FIG.1, showing additional details of the switching system.

FIG. 3A is a block diagram illustrating the switch hub shown in FIGS. 2Aand 2B.

FIG. 3B is a block diagram of the switch hub of FIG. 3A, showingadditional details of the hub.

FIG. 4 is a block diagram illustrating the system and card shown inFIGS. 3A and 3B.

FIG. 5A is a block diagram illustrating the port card shown in FIGS. 3Aand 3B.

FIG. 5B is a block diagram of the port card of FIG. 5A, showingadditional details of the port card.

FIG. 6 is a block diagram illustrating the digital card and the headsetcard of the audio connection device shown in FIGS. 2A and 2B.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention and its advantages are best understood byreferring to FIGS. 1 through 7D of the drawings, like numerals beingused for like and corresponding parts of the various drawings.

FIG. 1 is a block diagram of a communications network 10, including aFiber Optic Ring Connected Equipment (FORCE) system 12 according to theteachings of the invention. According to one embodiment, the system 12is a modern second generation, fully digital, fiber optic based audioswitching and distribution system. According to one embodiment, theFORCE system 12 functions to tie all of the audio sources anddestinations on a given platform together, and distribute data andsignals as required to meet the utilization needs of the network 10. Assuch there are several discrete functions that are provided by the FORCEsystem 12 according to one embodiment. Generally, these function areachieved by combining a star physical configuration with a synchronousTDMA data stream in a logical ring architecture. The followingparagraphs describe these functions.

The FORCE system 12 interfaces and controls a wide variety of equipment,including the following:

Radios 20: HF, UHF, VHF, SATCOM, and Navigational radios. Control forthis equipment nominally means activation of Push-To-Talk (PTT) linesand assorted mode discretes.

Cryptographic Device (CRYPTO) 22: KY-58, ANDVT, KY-75, and STU III, forexample. The system interfaces to both the Red and Black sides of thedevice, and can interconnect any selected CRYPTO device in line with anycompatible radio. This allows a single CRYPTO device 22 to bedynamically assigned to any radio without the use of external relays orswitching boxes. The FORCE system 12 handles the discrete interface andhandshaking with the CRYPTO device 22.

User Workstations, Modems, Headsets and Speakers 24: The FORCE system 12interfaces to a wide variety of headsets, and has been specificallydesigned to take advantage of stereo headsets when available to providebinaural sound. The system 12 handles multiple PTT signals, and easilyhandles aircraft control centers that utilize separate PTTs forinterphone and radio access. Fully adjustable VOX capabilities as wellas automatic gain control (AGC) are provided on all channels. The FORCEsystem 12 supports Active Noise Reduction (ANR) headsets as well.Loudspeaker drivers (not shown) are provided for publicaddress/broadcast needs.

The FORCE system 12 provides an open architecture and extra bandwidth tohandle a wide variety of non-traditional signals, such as video andserial data, for example, as included within video sources and displays21.

The FORCE system 12 supports a virtually unlimited number ofsimultaneous conferences, including both operators and equipment. Thefollowing are the major features of conferences available with the FORCEsystem 12.

Because the FORCE system 12 creates conferences digitally, the number ofconference channels the system supports is virtually unlimited. Theprimary limitation on the number of conferences provided in a system isthe access provided to the operator by the operator control panel.

The FORCE system 12 also supports having all users on a singleconference channel, or any subset thereof. Conferences can also includeradios and other equipment, and may be secure or clear. Specifiedconferences can be restricted to a subset of users, if desired.

In addition, the FORCE system 12 supports signaling on a station bystation basis as part of a platform LAN 19. A fixed group of stations(or an individual) can be signaled by transmitting a tone to anear/speaker and/or flashing a light on a control panel.

Further, the FORCE system 12 supports fixed/ringing conferences tosignal a fixed group of stations designated for the conference wheneverthe conference is activated. A user on the FORCE system 12 can alsobuild a conference dynamically, by signaling individual users and thenadding the users into a conference, similar to building a teleconferenceusing a standard phone system.

The FORCE system 12 allows any combination of audio channels to bemonitored at any or all stations. When monitoring, each channel hasindividually adjustable volume and azimuth (when using binauralheadsets) settings. Certain channels (i.e., aural warnings, PA) can beconfigure to always monitor at high (+6 dB) levels.

The FORCE system 12 has built-in support for point-to-point calling. Anynode on the ring can signal (“Dial”) and exclusively talk to anothernode in the system. This includes call hold, call waiting, caller ID,and busy signaling capabilities. In addition, all nodes in the systemhave real-time access to the conference, monitor, and calling status ofall other nodes on the ring.

The FORCE system 12 also handles many non-audio signals, including datasignals and special purpose wide-band signals by modems 23 andmultiplexers 25. For these signals, the system 12 provides thecapability to digitize and route signals in a one-to-one or one-to-manymode.

The operation and structure of the FORCE system 12 is described below inconjunction with FIGS. 2A through 7. FIG. 2A is a block diagram of theFORCE system 12 shown in FIG. 1, constructed according to the teachingsof the invention, and FIG. 2B is another block diagram of the FORCEsystem 12 shown in FIG. 1, showing additional details of the system.

The FORCE system 12, according to the embodiment illustrated in FIGS. 2Aand 2B, includes three major components: an interconnect hub 14, audioconnection devices (ACDs) 16, and control panels 18 (FIG. 2B), to bedescribed in greater detail below in conjunction with subsequentFIGURES.

In this embodiment, interconnect hub 14 is a ¾ ATR, 36 port box at thecenter of the system, and ties together all of the ACDs 16 in thesystem. Multiple interconnect hubs 14 may be tied together to provideadditional flexibility or survivability if desired. It should beunderstood the interconnect hubs 14 of other sizes may also be used.

Audio Connection Devices (ACDs) are usually small boxes typicallymounted close to the operators or equipment that is being tied into thesystem. Each ACD 16 can handle 4 to 6 audio channels, and is responsiblefor digitizing and mixing the audio for each channel, and interfacingwith the fiber optic ring. In addition, each ACD 16 has multiplediscrete inputs and outputs for controlling equipment and interfacingwith operator Push-to-talk (PTT) signals. Each ACD 16 also providesmultiple serial ports to interface control panels into the system.

Control panels 18 (shown best in FIG. 2B) provide the operator interfacefor the system, and are usually unique to each given application. Thereis illustrated a simple standard RS-232/RS-422 serial interfaces and astraight forward protocol for control of the system, thereby allowingthe control panel to be anything from a standard “switches & knobs” typeof panel to a CDU or even a computer, as desired for the givenapplication.

The FORCE system 12 utilizes a fiber optic concentrated ringarchitecture, wherein the interconnect hub 14 connects multiple AudioConnection Devices 16 together to form a network. The system asillustrated can accommodate up to 256 ACDs 16 in each system. Since eachACD 16 can support multiple audio channels, the system can easily handlehundreds of audio channels.

The system operates by digitizing all signals received at a given ACD 16and placing the digitized signals into designated timeslots in the dataframes that are passed around the fiber optic ring 27. Thus, every uniton the ring has access to the signal data being received from everyother unit on the ring in real time. A frame is passed around the ring27 every 125 microseconds (8 KHz frame rate), and thus the latency fromthe time a signal is digitized to the time it is output to the desiredchannels will be 125 microseconds.

A portion of the data packets passed around the ring 27 is allocated asa message channel. The message channel is utilized by all nodes on thering to communicate status and commands. The message channel has over 5Mb/s of throughput, and operates at the same 8 KHz rate as the rest ofthe ring. Messages can be passed from control panels through the ring toremote ACDs 16, allowing any control panel to access and control any orall nodes on the system. The message channel can also be used to uploadnew Operational Flight Programs (OFPs) to all ACDs on the ring.

Referring to FIG. 2B, control panels 18 for the system 12 are interfacedthrough the nearest ACD 16, eliminating the requirement to wire all theway back to a central unit. Each ACD 16 can handle up to 4 controlpanels. Because every application has unique control panel requirements,the architecture of the system 12 makes no attempt to require aparticular type of control panel. Instead, the architecture defines astandard RS-232/RS-422 serial interface and protocol, and theapplication determines how the control panel should look and behave.This interface can easily accommodate any type of control panel from aGUI-based computer to a smart CDU to the more common “switches andknobs” type control panel. The interface and protocol provided forcontrol panels provides full access to the entire FORCE system. Whilethe FORCE system was designed to utilize distributed control, the entiresystem could be controlled from a single control panel or computerattached to any ACD in the system if desired.

A DSP 36 (FIG. 4) in each ACD 16 chooses the audio channels to be mixedtogether based on commands and status received from the data channel 37,and places the audio on the output channel(s) 39 of the ACD 16. Becauseall channels are available to all nodes and mixed by software, there areno arbitrary limitations on the number of conference channels availableor the connections that can be made.

The ring 27 utilizes the Synchronous Optical Network (SONET) standardfor physical layer data transmission, operating at the OC-3 level (155Mb/s). This bandwidth allows the system to handle over a thousandtelephone grade audio signals, or hundreds of higher fidelity signals.SONET was developed by the telecommunications industry and forms theheart of all telecommunications call trunking and switching equipment.It is also the same standard used for ATM local area networking. Currentapplications of SONET have been implemented at OC-48 (2.48 Gb/s) andabove, allowing for a ready upgrade path should additional bandwidthever be desired. Because SONET technology is widely deployed for bothnetworking and telecommunications applications, it should be widelyavailable and supported for many years.

The concentrated ring architecture is extremely robust and easilyreconfigurable. In the FORCE system 12, the interconnect hub 14automatically adjusts to the number of ports installed in the hub 14 andthe number of active units in the system by bypassing any inactive portin the interconnect hub. This architecture survives multiple ACD 16 orport failures (or equipment removals/power downs) without loss offunctionality. Also, this capability precludes the need for the poweredjunction boxes to keep the ring 27 alive while a unit is powered off orremoved.

Also, as shown in FIG. 2A, the interconnect hub 14 itself incorporatesdual counter-rotating rings 17 internally to ensure that single pointfailures do not prevent data from moving around the ring. Theinterconnect hub also incorporates dual redundant load sharing powersupplies and dual fans, to ensure that the system continues operatingeven with a power supply or fan failure.

The FORCE system 12 can handle Red/Black isolation and other Tempestsecurity issues. Tempest guidelines require that security issues beconsidered from both digital and analog perspectives, to insure thatclassified data can not be inadvertently compromised.

From an analog perspective, the FORCE system 12 ensures that Red(classified) signals are well isolated from Black (non-classified)signals, since black signals can be broadcast to the world on any one ofthe various radios in a system. The usual problems occurring here arethe electromagnetic coupling/crosstalk of a red signal onto a blacksignal in cabling and/or through the circuitry inside of a box. Tempestrequires a (lower) level of separation for red-to-red situations.

Within the FORCE system 12, coupling and crosstalk can only occurbetween the signals being handled in a single ACD 16, since ACDs 16 haveno electrical connection to each other. Several measures are taken toensure minimizing crosstalk.

Each signal is brought into the unit on a separate connector, allowingthe signal shielding to remain intact all the way into the box.

Inside the box, the signals are connected to the interface card via flexcabling, allowing separation of the signals to be repeatably maintained(this would not be easily achievable if the connectors were discretelywired).

On the interface card for the cryptos 22, each signal is handled byseparate circuitry utilizing a separate ground and power plane. Physicalseparation is also provided between the circuitry for two channels.Where Red and Black signals can occur within a single box, (i.e., amulti-operator ACD), separate power supplies are used for each channelto provide additional isolation.

The ACD 16 removes all Red signals from the mix being sent to a headsetwhile that headset is keyed (PTT depressed) for a Black transmission, topreclude coupling of Red audio from the headset to the microphone.

Once digitized, care must also be taken to ensure that red and blacksignals are kept isolated. While crosstalk and electromagnetic effectsare not a significant issue in the digital domain, safeguards must beput in place to make sure that software does not accidentally mix a redsignal with a black signal, or connect a red source to a blackdestination. The FORCE system 12 has the following safeguards topreclude these situations.

Each ACD 16 is strapped in hardware to indicate the highest securitysignal it is authorized to handle, and will ignore any requests toprocess data of a higher security level.

Each signal is tagged with an appropriate classification level when puton to the ring. In addition, each classified signal is encoded such thatif accidentally mixed into an audio signal without decoding, it will beunintelligible. An ACD 16 will not tag anything to a higher level thanit is authorized to handle.

Each conference is also tagged with a security level, and the ACD 16will ignore any signals intended to be in the conference who are not atthis level.

Classified signals are decoded and mixed only if 1) the ACD 16 isstrapped to handle this level of data, 2) the intended conference is atthat level, and 3) the data is tagged at that level.

Additional restrictions can be incorporated into the control panels 18to ensure that the user is authorized to access a given signal.

Collectively these safeguards ensure that no single software failurecauses a signal to be inadvertently compromised.

FIG. 3A is a block diagram illustrating interconnect hub 14 of FIGS. 2Aand 2B, FIG. 3B is also a block diagram of hub 14, illustratingadditional details. The interconnect hub 14 is a standard ¾ ATR talllong chassis that houses an 8 slot VME-64 card cage, dual redundantpower supplies and dual fans.

Cards plugged into the card cage provide the functionality of theinterconnect hub 14. The chassis houses one system card 30 and up to 6port cards 32. One slot 34 is spare, available for any uniqueapplication needs. Front panel connectors include a hub expansionconnector and three (3) ACD fiber connectors. Each of the ACD connectorsprovides access to 12 pairs of standard 62.5/125 multimode fiber,allowing up to 12 ACDs 16 to be connected to an ACD connector.Additional details of and connection within system card 30 and port card32 are illustrated in FIG. 2B and described in greater detail below inconjunction with FIGS. 4, 5A, and 5B.

FIG. 4 is a high level block diagram illustrating system card 30 ofFIGS. 3A and 3B. The system card 30 provides several capabilities foroperation of the FORCE system 12. The primary function of the systemcard 30 is to electrically connect the fiber rings from all the portcards 32 in the chassis to each other bypassing any port card slots thatare not in use. The bus synchronizer (BSU) 34 functions to maintain the8 KHz frame rate of the ring and minimizes stale data from the ring.Because the ring can not operate without a BSU 34, the system cardactually provides dual redundant BSUs.

The system card also includes a DSP 36 (the same one used in the ACDs).This processor is not required for normal operation of the system, andis provided to perform diagnostic (BIT) functions for the interconnecthub 14. Since the processor has full access to the ring data, as well asto the VME bus within the interconnect hub chassis, the DSP 36 can alsobe used to provide access to data on the ring from any card on the VMEbus. This is used to satisfy unique application requirements.

FIGS. 5A and 5B are block diagrams illustrating port card 32 of FIGS. 3Aand 3B. A port card 32 interfaces up to 6 ACDs 16 into the system andcan be installed into any of the 6 port card slots in the hub chassisallowing for the connection of up to 36 ports into a single hub. Eachport monitors the incoming signals from the ACD 16 and neighboring portsfor signal activity, and will take corrective action on detection of afailure. If the signal coming from an ACD 16 fails (optical carrier orclock is lost) that ACD 16 will be bypassed. This situation can happenwhen an ACD 16 fails or when powered off. In any event, if the signalreturns, the connection to the ACD 16 is restored.

If the signal from a neighboring port 32 fails, the port will activate asecondary ring to loop around the failed port. The port circuit oneither side of the failed unit loops the primary ring to the secondaryring, thus cutting the failed port out of the ring.

FIG. 6 is a block diagram illustrating the audio connection device 16 ofFIG. 2A, including a digital card 38 and a headset interface card 40.ACD 16 is the workhorse of the FORCE system 12. It has theresponsibility of digitizing the analog inputs for transmission on tothe fiber optic ring 27 and the mixing and processing of the digitaldata from the ring 27 to create the specified audio outputs.

The ACD 16 physically consists of two circuit cards, the digital card 38and the interface card 40. Digital card 38 contains the TMS320C6201 DSP42 (200 MHZ, 1600 MIP), the power supply for the ACD, and all circuitryrequired to interface to the fiber optic ring 27. Also comprising thedigital card 38 are 4 serial ports 44 for interfacing with controlpanels or other equipment, 2 MB of EEPROM for program memory, and 32 KBof non-volatile memory for storage of configuration and fault data. Inaddition, the digital card 38 contains an industry standard PCIMezzanine Card (PMC) 46, hosting the interface card for the ACD 16. ThisPMC 46 can be used for one of the custom interface cards or can bepopulated with any commercial off-the-shelf (COTS) PMC card (1553, T-1,ISDN, Video, etc.) The digital card 38 is common to all ACDs 16.

The interface card 40 varies depending on the intended use of theparticular ACD 16. Several types of interface cards may be used, such asa headset interface card (illustrated) and an equipment interface card.These cards are further described below.

The headset interface card 40 is specifically designed to handle all ofthe interfaces that are likely to be associated with in operator. Theheadset card is nominally intended to service two operators, each with aslaved spare headset connection. Each operator then also has a speakerinterface and auxiliary line/modem interface. Each of the headsetinterfaces is separately digitized, and therefore can be utilized asfour separate operator interfaces if spare headset connections are notrequired.

The headset card provides four independently controllable stereo or monoheadset interfaces 48. The card can be configured to use powered orunpowered microphones, each with independent automatic gain control(AGC). Independent Voice Operated Transmission (VOX) capability for eachchannel is provided digitally by the DSP. A total of 8 input discretes54 are provided to handle multiple Push-To-Talk (PTT) inputs and twoindependent speaker channel drivers 52 are provided for driving a 3 voltsignal into a 150 to 600 ohm speaker. Two auxiliary channel modems 50are provided which can be independently switched under program controlbetween a standard line level (1 Vrms) signal suitable for interface toa computer or other COTS audio equipment, or a standard 2 wire phoneinterface, suitable for connection to a computer modem or standardtelephone. Independent circuitry powered from a separate 28 VDC powerinput is provided to connect headset #1 to an emergency audio port. Theemergency audio port is a standard 600 ohm audio interface with anassociated PTT signal. This port is operable anytime the emergency poweris available, whether or not the rest of the ACD 16 is powered. It isactivated via an emergency input discrete 54.

All audio channels utilize independent CODEC channels 56, and audiobandwidths from 4 KHz to 24 KHz can be supported. Headsets #1 and #2 andassociated circuitry utilize a separate power source from headsets #3and #4 and circuitry associated therewith to provide the isolationrequired for red/black separation between these channels. The emergencycircuitry is powered from a third power source.

The interface card 40 is designed to handle standard radio andcryptographic equipment. Because of the flexibility inherent in thedesign of the interface card, it can also interface most other specialpurpose equipment that may be called for in any given situation.

The card is configurable to handle bandwidths up to 40 KHz, balanced orunbalanced lines, and a 135 to 600 ohm impedance. Four ports areprovided per card, each with 4 input and 4 output discretes 54 forconfiguration and control of the connected equipment. Each interface isprovided with a circular connector for quick connect/disconnect. Allsignal lines to and from the interface card 40 have built in surge/HERFprotection.

Because the mechanical and electrical connection to the interface card40 utilizes the industry standard PMC specification, the ACD 16 acceptsCOTS PMC cards to provide special purpose interface capabilities to thesystem. PMC cards are readily commercially available to handle standardinterfaces such as MIL-STD-1553, ARINC-429, and many telecom interfaces(T-1/E-1 and ISDN, for example).

Technical Specification Summary

Below is a table summarizing technical specifications for components ofone embodiment of the invention; however, other specifications may beutilized without departing from the scope of the present invention.TABLE 1 Technical Specification Summary Force System SpecificationsInterconnect HUB 32 Specifications (¾ ATR Version) Power RequirementAC - 115 VAC, 47 to 440 Hz @ 180 watts Size: ¾ ATR, tall, long,, Fiber:SONET, OC-3, 155 Mb/s Backplane: VME 64, 8 slots System Card Power: 30watts Size: VME 64, 6U Port Card Power: 30 watts Size: 6U VME ACD 16Specifications Power Requirement DC - 18 to 32 VDC @ 18 watts Size:6.75″ W × 7.5″ L × 2.0″ H Headset Interface: Microphone Bias M-7A,M-7/DC, M-1/DC Hdst - Unbias M-87, M-101 Mono: 8 to 600 ohms Stereo: 8to 300 ohms Loud Speaker 150 to 600 ohms I/F Line Interface: Out- 600ohm, 1 Vrms In- 600 ohm, 1 Vrms Equipment Interface: Out - 135 to 600ohms, 5 Vrms In - 135 to 600 ohms, 5 Vrms Digital Card DSP: TMS320C6201200 MHZ, 1600 Mip Fiber: SONET, OC-3 level Program Memory: 2 MbytesEeprom Configuration 32 kbytes, non-volatile Memory:

Although the present invention has been described with reference toseveral embodiments, changes and modifications may be suggested to oneskilled in the art, and it is intended that the present inventionencompass such changes and modifications as fall within the scope of thepresent appended claims. Further modifications and alternativeembodiments of the techniques described herein will be apparent to thoseskilled in the art in view of this description. It will be recognized,therefore, that the techniques described herein are not limited by theseexample arrangements. Accordingly, this description is to be construedas illustrative only and is for the purpose of teaching those skilled inthe art the manner of carrying out the techniques described herein. Itis to be understood that the forms of the techniques described hereinshown and described are to be taken as the presently preferredembodiments. Various changes may be made in the implementations andarchitectures. For example, equivalent elements may be substituted forthose illustrated and described herein and certain features of thetechniques described herein may be utilized independently of the use ofother features, all as would be apparent to one skilled in the art afterhaving the benefit of this description of the techniques.

1. A method of communicating data among a plurality of devices,comprising: providing at least one interconnect hub; providing aplurality of connection devices each of which is configured to connectto one or more signal sources; physically connecting the connectiondevices to the interconnect hub to form a network having a physical starconfiguration with the interconnect hub as a center; logicallyconnecting the connection devices using the interconnect hub to form alogical ring configuration so that each connection device has access toeach digital data packet sent by any other connection device as itpasses around the logical ring; and communicating digital data packetsbetween the connection devices through the interconnect hub usingsynchronous communications based upon a common clock signal, wherein atleast a portion of the digital data packets include data representingsignals from the signal sources.
 2. The method of claim 1, wherein thecommunicating step comprising communicating digital data packets betweenthe connection devices using data frames passed around the logical ringin designated time slots.
 3. The method of claim 2, wherein thecommunicating step comprises transmitting the data frames around thering network at a rate of at least 8 KHz.
 4. The method of claim 1,further comprising receiving analog signals at one or more of theconnection devices, and digitizing the analog signals to form digitaldata signals for the communicating step.
 5. The method of claim 1,further comprising controlling each connection device utilizing controlpanel individually coupled to the connection device.
 6. The method ofclaim 1, further comprising communicating at least in part digital datapackets including data representing audio signals from the signalssources to the connection devices.
 7. The method of claim 1, furthercomprising communicating at least in part digital data packets includingdata representing video signals from the signals sources to theconnection devices.
 8. The method of claim 1, further comprisingcommunicating at least in part digital data packets including messagedata between at least two connection devices.
 9. The method of claim 8,where the message data comprises commands, and further comprisingallowing one connection device to control another connection devicethrough at least one command.
 10. A communications system comprising: aninterconnect hub; and a plurality of connection devices coupled to theinterconnect hub, each connection device being configured to beconnected to one or more signal sources; wherein the interconnect huband connection devices are physically connected to form a physical starconfiguration with the interconnect hub as a center; wherein theconnection devices are logically connected through the interconnect hubto form a logical ring configuration so that each connection device hasaccess to each digital data packet sent by any other connection deviceas it passes around the logical ring; wherein all communications ofdigital data packets between the connection devices through theinterconnect hub are configured to utilize synchronous communicationsbased upon a common clock signal; and wherein at least a portion of thedigital data packets include data representing signals from one or moresignal sources.
 11. The communications system of claim 10, wherein atleast one connection device is configured to convert analog signals fromthe signal sources to digital data signals.
 12. The communicationssystem of claim 10, wherein the interconnect hub is configured tocommunicate digital data packets using data frames passed around thelogical ring in designated time slots.
 13. The communications system ofclaim 12, wherein the data frames are communicated around the ringnetwork at a rate of at least 8 KHz.
 14. The communications system ofclaim 10, wherein the wherein the interconnect hub comprises a pluralityof fiber optic network connections for the plurality of connectiondevices.
 15. The communications system of claim 10, wherein theinterconnect hub comprises dual counter rotating fiber optic rings forsingle point failure protection.
 16. The communications system of claim15, wherein the fiber optic network connections provide a fiber opticconcentrated ring having a plurality of subloops equal in number to theplurality of connection devices, wherein each subloop couples to atleast one of the connection devices.
 17. The communications system ofclaim 16, wherein the interconnect hub further comprises a plurality ofports individually coupled to a subloop of the fiber optic concentratedring.
 18. The communications system of claim 10, further comprising aplurality of control panels individually coupled to the plurality ofconnection devices.
 19. The communications system of claim 10, whereinthe digital data packets comprise at least in part data representingaudio signals from the signals sources to the connection devices. 20.The communications system of claim 10, wherein the digital data packetscomprise at least in part data representing video signals from thesignals sources to the connection devices.
 21. The communications systemof claim 10, wherein the digital data packets comprise at least in partdata representing message data between at least two connection devices.22. The communications system of claim 21, where the message datacomprises at least one command from a first connection device to asecond connection device, the command allowing the first connectiondevice to control the second connection device.